When extracted, crude oil may contain a number of undesired compounds or contaminants, such as sulfur compounds. Reduction in the amount of sulfur compounds in automotive fuels and other refined hydrocarbons is typically required in order to meet environmental concerns and governmental regulations. Further, sulfur compounds often adversely impact refinery operations, e.g., by poisoning catalysts. In many hydrocarbon processing schemes, sulfur is removed from the hydrocarbon feedstock by catalytic hydrodesulfurization in hydrotreating process units.
Crude oils also may contain various organic nitrogen species in quantities that impact the refinery processing of the crude oils fractions. Specifically, the presence of organic nitrogen species in the hydrocarbon feedstock may suppress the hydrodesulfurization function of hydrotreating catalysts and require relatively higher operating pressure. This suppression is particularly troublesome for older hydrotreating process units that have relatively lower limits on operating pressure. As a result, older hydrotreating process units cannot process hydrocarbon streams having relatively high organic nitrogen species content, such as cracked feedstocks.
Hydrodesulfurization suppression is also problematic for selective hydrotreating processes that are inherently constrained by low operating pressure. For example, processes for forming high octane product streams require relative lower operating pressures during hydrotreating. Therefore, hydrocarbon streams with a relatively high organic nitrogen species content cannot be processed into high octane products without a reduction in organic nitrogen species content.
Accordingly, it is desirable to provide methods and apparatuses for processing hydrocarbon streams containing organic nitrogen species. Further, it is desirable to provide methods and apparatuses that continuously contact hydrocarbon streams with aqueous acidic solutions to react with and remove organic nitrogen species from the hydrocarbon streams. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.